Abstract

We discuss the properties of the transmission function in the k-space for a generic multi-layered structure. In particular we analytically demonstrate that a transmission greater than one in the evanescent spectrum (amplification of the evanescent modes) can be directly linked to the guided modes supported by the structure. Moreover we show that the slope of the phase of the transmission function in the propagating spectrum is inversely proportional to the ability of the structure to compensate the diffraction of the propagating modes. We apply these findings to discuss several examples where super-resolution is achieved thanks to the simultaneous availability of the amplification of the evanescent modes and the diffraction compensation of the propagating modes.

Figures (12)

(a) TM dispersion curves for the guided modes of a 4 period structure (d1d2)4 with d1 = d2 = 40nm. (b) log10(T + 1) of the evanescent components vs. λ and kx/k0 with no absorption. (c) Same as (b) but with small absorption. (d) Same as (b) but with consistent absorption.

Free space diffraction of the z-component of the Poynting vector in arbitrary units from 4 slits located at z = 0. The 4 slits are symmetrically located with respect to the axis x = 0. The two inner slits are 50nm wide and have a distance center to center of 150nm. The two outer slits are 250nm wide and have a distance center to center of 600nm.

(a) Free space diffraction of Sz from the 4 slits. (b) Diffraction with the lens in front of the scattering object for TE polarization. (c) Diffraction for TM polarization. (d) Section of Sz at z = 391nm (i.e. 50nm beyond the end of the lens). Superimposed (black line) the position of the 4 slits.

Diffraction with a metallo-dielectric lens whose number of periods is triple with respect to the lens described in Fig. 5. (a) TM polarization. (b) TE polarization. (c) Section of Sz at z = 500nm, i.e. in the middle of the lens. (d) Section of Sz at z = 1200nm, i.e. ~180nm beyond the output surface of the lens.

Diffraction with a metallo-dielectric lens whose number of periods is eight times greater than the lens described in Fig. 5. (a) TM polarization. (b) TE polarization. (c) Section of Sz at z = 2.73μm, i.e. few nanometers beyond the end of the lens. Superimposed the position of the slits.